Airconditioning ducting is available in standard sizes, and it is desirable that an air cooler should be positionable on and supported by the upper end of a length of standard size airconditioning ducting. It will be appreciated that quite often the fitting is in an elevated position and sometimes in the space between a roof and ceiling, and it is most desirable that fitting operation should be as simple as possible. Furthermore, when an evaporative air cooler is used of the type described in the said Application PG2041, the cooling water is turbulent and there is an inherent danger of malfunction which may result in water being released from the base of the airconditioner. It is important that such water should not enter the duct where it can cause excessive humidity, interfere with the efficiency of thermal insulation, and/or possibly result in the development of an objectionable odour.